For example, in wiring connection inside various electrical appliances or in connection between various electrical appliances, as shown in FIG. 24, electrical connection work is conducted using a terminal block 900, which is divided into a plurality of sections by walls 90, 92, to fasten a lead line and a conductive plate 94 by a bolt 922 with a washer 98 provided therebetween.
On this occasion, a worker required to conduct bolt fastening work for numerous terminals or a worker required to conduct such work for a long period of time often needs more time for confirming that each bolt is securely fastened or not. Additionally, from a point of view of workability, a worker may insert a driver into a groove 922 of a bolt 921 and conduct so-called temporary fixing, that is, turning the driver to some extent and then stop turning. In such a case, failing to confirm a fastening degree of the bolt increases a possibility that various problems occur due to insufficient electrical connection. Additionally, when working in a dark place or a limited area, a worker may have a difficulty in confirming a final fastening degree of a bolt.
In particular, since a recent photovoltaic power generation system, which is represented by a term, mega solar, includes numerous terminal blocks, for example, the above-described work using a bolt for electrical connection may be a considerable work-load for workers.